1. Field of the Invention
The present invention relates to a module substrate including a terminal connection substrate that is connected to a base substrate including a plurality of electronic components that are mounted on at least one surface thereof, and a method for manufacturing a module substrate.
2. Description of the Related Art
In recent years, with reductions in the size and weight of electronic devices, module substrates mounted in electronic devices have been required to be reduced in size and weight. Thus, a module substrate is reduced in size and weight by mounting electronic components on both surfaces of a base substrate via a lead terminal, a solder ball, a cavity structure, or other suitable structure.
Japanese Unexamined Patent Application Publication No. 2004-303944 discloses a module substrate that includes a main substrate in which a plurality of electronic components are mounted on both surfaces thereof by soldering, and four sub-substrates that have a substantially rectangular parallelepiped shape and are mounted on the outer periphery of the main substrate by soldering. Each sub-substrate includes electrodes having a U shape on a surface of a base material. In addition, in Japanese Unexamined Patent Application Publication No. 2004-303944, a resin is applied to a portion surrounded by the sub-substrates, so as to cover the electronic components. Thus, the module substrate can easily be manufactured without requiring special wiring, and can be automatically mounted on a mother substrate via a machine.
Since each sub-substrate disclosed in Japanese Unexamined Patent Application Publication No. 2004-303944 has a substantially rectangular parallelepiped shape, a cross-sectional area thereof is uniform. Thus, when the cross-sectional area of each sub-substrate is increased in order to securely connect the sub-substrate to the mother substrate, a region in which electronic components can be mounted is relatively small. When the region in which electronic components can be mounted is small, the number of mountable electronic components is reduced, the size of the module substrate itself needs to be increased in order to mount the same number of electronic components, and thus, the size of the module substrate cannot be reduced.